CHARLOTTE, NC (Katherine Peralta/The Charlotte Observer) - Chick-fil-A has added a new gluten-free bun to its menu. It’s now available at all of its restaurants nationwide.

The menu update is Chick-fil-A’s latest effort to cater to health-conscious customers. Last year, the Atlanta-based chain swapped out its Asian salad for a new spicy Southwest salad with fewer calories, for example. The chain also replaced its coleslaw last year with a lighter “superfoods” kale salad.

Chick-fil-A said Monday that the bun is made with a mix of ancient grains like millet, quinoa, sorghum, amaranth and teff. It comes individually packaged and can be ordered with any Chik-fil-A sandwich, the company said. The bun has 150 calories and costs an additional $1.15.

Chick-fil-A said it unveiled the new bun after extensive testing last year. Roughly 18 million people have gluten-sensitivity or preference, the company said, citing national data. The chain said it is now one of “the few quick-service restaurants” to sell a gluten-free bun.

Chick-fil-A operates about 40 restaurants throughout the Charlotte metro area.